Depth setters are well known and widely marketed for at least the past 20 years. Such devices are typically attached to the working end of a power tool such as a hand-held power drill for drilling holes and driving screws. In the latter role, the depth setter includes a distal end having a centrally located screw bit tip which fits onto the head of a screw and a cylindrical collar with an edge portion extending therearound, and an attachment end which attaches to the drive mechanism of the power tool. During driving of the screw into a workpiece, the cylindrical collar acts as a stop when the edge portion contacts the surface of the workpiece at a predetermined depth.
The depth setter may include a clutch mechanism for interrupting transmission of torque to the screw upon reaching a predetermined depth of screw penetration to prevent damage to the screw and the workpiece. During operation, the screw bit tip engages the screw until the cylindrical collar contacts the surface of the workpiece. Once contact is made, the clutch mechanism disengages the screw bit tip from the screw. An example of a depth setter is shown and disclosed in U.S. Pat. No. 4,287,923 issued to Homung.
The depth setter may further include an adjustment feature which allows the user to vary the depth of the screw. An example of an adjustable depth setter is the Hex Shank Non-Magnetic Adjustable Screw Depth Setter Model No. DW2043 marketed by DeWalt Industrial Tool Co. of Baltimore, Md. The depth setter may also include a freed spinning collar to minimize the possibility of the edge portion of the collar marring the workpiece surface. An example of a depth setter with this type of collar is the Depth Driver 1 Model No. 2420 marketed by Wolfcraft GmbH of Kempenich, Germany.
Although a free spinning collar minimizes marring, surface damage can still occur in some materials and under certain conditions. In some instances, the spinning collar can burnish the surface before it completely stops rotating due to inertia. This can occur most often in dense hardwoods with smoothly sanded surfaces, and in softer materials such as PVC trim boards. This problem is particularly acute when the angle of the depth setter is less than normal to the workpiece surface (i.e., less than 90°). Collars in prior art depth setters are generally configured with sharp 90° edges that can cut into or easily dent the surface of workpieces particularly softer materials before engagement of the clutch mechanism.
Accordingly, there is a need for a depth setter for use with rotary-type power tools, configured for minimizing marring or other damage to the surface of a workpiece. Furthermore, there is a need for a depth setter that is simple and cost efficient to make and use. Finally, there is a need for such depth setters with fixed as well as with adjustable depth settings.